Adhesive compositions containing graphenic carbon particles

ABSTRACT

Disclosed herein are adhesive compositions comprising (a) a first component; (b) a second component that chemically reacts with said first component; and (c) graphenic carbon particles having an oxygen content of no more than 2 atomic weight percent. Disclosed herein are associated methods for forming the adhesive compositions and applying the adhesive compositions to a substrate to form a bonded substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 13/463,105,filed May 3, 2012, entitled “Adhesive Compositions Containing GraphenicCarbon Particles,” which is a continuation-in-part of U.S. patentapplication Ser. No. 13/315,518, filed Dec. 9, 2011, entitled“Structural Adhesive Compositions”, which is a continuation-in-part ofU.S. patent application Ser. No. 12/949,878, filed Nov. 19, 2010 andentitled “Structural Adhesive Compositions.”

FIELD OF THE INVENTION

The present invention relates to adhesive compositions and moreparticularly to 1K and 2K adhesive compositions.

BACKGROUND INFORMATION

Adhesives are utilized in a wide variety of applications to bondtogether two or more substrate materials. For example, adhesives may beused for bonding together wind turbine blades or bonding togetherautomotive structural components.

The present invention is directed towards one-component (1K) andtwo-component (2K) adhesive compositions that provide sufficient bondstrength, are easy to apply, and, where applicable, have sufficientlylong pot lives for use in bonding together substrate materials.

SUMMARY OF THE INVENTION

One embodiment of the present invention discloses a compositioncomprising (a) a first component; (b) a second component that chemicallyreacts with the first component; and (c) graphenic carbon particleshaving an oxygen content of no more than 2 atomic weight percent.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plot of Raman shift versus intensity for a sample ofmaterial according to Example A.

FIG. 2 is a TEM micrograph of a sample of the material producedaccording to Example A.

DETAILED DESCRIPTION

For purposes of the following detailed description, it is to beunderstood that the invention may assume various alternative variationsand step sequences except where expressly specified to the contrary.Moreover, other than in any operating examples, or where otherwiseindicated, all numbers expressing, for example, quantities ofingredients used in the specification and claims, are to be understoodas being modified in all instances by the term “about”. Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe following specification and attached claims are approximations thatmay vary depending upon the desired properties to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard variation found in theirrespective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between (andincluding) the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10.

In this application, the use of the singular includes the plural andplural encompasses singular, unless specifically stated otherwise. Inaddition, in this application, the use of or means “and/or” unlessspecifically stated otherwise, even though “and/or” may be explicitlyused in certain instances.

As used herein, the term “curing” refers to the toughening or hardeningof a polymer material by cross-linking of polymer chains.

As noted above, in general, the present invention discloses 1K(“One-Component”, or “One Part”) and 2K (“Two-Component”, or “Two Part”)adhesive compositions that are used to bond together two substratematerials for a wide variety of potential applications in which the bondbetween the substrate materials may provide particular mechanicalproperties related to elongation, tensile strength, lap shear strength,T-peel strength, modulus, or impact peel strength. The adhesive isapplied to either one or both of the materials being bonded. The piecesare aligned and pressure and spacers may be added to control bondthickness.

As defined herein, a “1K” adhesive composition, is a composition inwhich all of the ingredients may be premixed and stored and wherein thereactive components do not readily react at ambient or slightly thermalconditions, but instead only react upon activation by an external energysource (such as by thermal means or by actinic radiation). By contrast,a 2K adhesive composition is a composition in which the reactivecomponents readily react and cure without activation from an externalenergy source, such as at ambient or slightly thermal conditions. Asfurther defined herein, ambient conditions generally refer to roomtemperature and humidity conditions or temperature and humidityconditions that are typically found in the area in which the adhesive isbeing applied to a substrate, while slightly thermal conditions aretemperatures that are slightly above ambient temperature but aregenerally below the curing temperature for the adhesive composition(i.e. in other words, at temperatures and humidity conditions belowwhich the reactive components will readily react and cure).

Relatedly, the present invention also provides a method for formingthese 1K and 2K adhesive compositions, and also provides a method forimproving the rheology and other features of these 1K and 2K adhesivecompositions.

Suitable substrate materials that may be bonded by the adhesivecompositions include, but are not limited to, materials such as, metalsor metal alloys, natural materials such as wood, polymeric materialssuch as hard plastics, or composite materials. The adhesives of thepresent invention are particularly suitable for use in variousautomotive applications and for use in wind turbine technology.

2K Adhesives

The 2K adhesives of the present invention are formed from two chemicalcomponents, namely, (a) a first component and (b) a second componentwhich are mixed just prior to application. For 2K adhesives, the curingbetween the first component (a) and the second component (b) to form thecrosslinked final product occurs immediately upon mixing at ambient orslightly thermal temperatures (i.e. without the need for an externalenergy source such as an oven or actinic radiation source).

The first component (a), in certain embodiments, comprises one or moreepoxy compound and/or epoxy-adducts. The second component (b), incertain embodiments, comprises a curing component that reacts with thefirst component to form a bond (i.e. it crosslinks with the firstcomponent, typically through the epoxy groups) that provides thesubstrate to which it is applied with desirable bonding characteristics.In certain embodiments, the curing component is an amine compound,although other curing components such as thiol-functional (—SH)compounds may alternatively be utilized.

The equivalent ratio of amine to epoxy in the adhesive composition mayvary from about 0.5:1 to about 1.5:1, such as from 1.0:1 to 1.25:1. Incertain embodiments, the equivalent ratio of amine to epoxy is slightlyabove 1:1. As described herein, the equivalents of epoxy used incalculating the equivalent ratio of epoxy are based on the epoxyequivalent weight of the first component, and the equivalents of amineused in calculating the equivalent ratio of amine are based on the aminehydrogen equivalent weight (AHEW) of the second component.

Suitable epoxy compounds that may be used as the first component includepolyepoxides. Suitable polyepoxides include polyglycidyl ethers ofBisphenol A, such as Epon® 828 and 1001 epoxy resins, and Bisphenol Fdiepoxides, such as Epon® 862, which are commercially available fromHexion Specialty Chemicals, Inc. Other useful polyepoxides includepolyglycidyl ethers of polyhydric alcohols, polyglycidyl esters ofpolycarboxylic acids, polyepoxides that are derived from the epoxidationof an olefinically unsaturated alicyclic compound, polyepoxidescontaining oxyalkylene groups in the epoxy molecule, and epoxy novolacresins. Still other non-limiting first epoxy compounds includeepoxidized Bisphenol A novolacs, epoxidized phenolic novolacs,epoxidized cresylic novolac, and triglycidyl p-aminophenol bismaleimide.

In one embodiment, the epoxy-adduct is formed as the reaction product ofreactants comprising a first epoxy compound, a polyol, and an anhydride.In another embodiment, the epoxy-adduct is formed as the reactionproduct of reactants comprising a first epoxy compound, a polyol, and adiacid. In still another embodiment, the epoxy-adduct is formed as thereaction product of reactants comprising a first epoxy compound, apolyol, an anhydride, and a diacid. In these embodiments, theepoxy-adduct comprises from 3 to 50 weight percent such as from 3 to 25weight percent of the first component.

Useful first epoxy compounds that can be used to form the epoxy-adductinclude polyepoxides. Suitable polyepoxides include polyglycidyl ethersof Bisphenol A, such as Epon® 828 and 1001 epoxy resins, and Bisphenol Fdiepoxides, such as Epon® 862, which are commercially available fromHexion Specialty Chemicals, Inc. Other useful polyepoxides includepolyglycidyl ethers of polyhydric alcohols, polyglycidyl esters ofpolycarboxylic acids, polyepoxides that are derived from the epoxidationof an olefinically unsaturated alicyclic compound, polyepoxidescontaining oxyalkylene groups in the epoxy molecule, and epoxy novolacresins. Still other non-limiting first epoxy compounds includeepoxidized Bisphenol A novolacs, epoxidized phenolic novolacs,epoxidized cresylic novolac, and triglycidyl p-aminophenol bismaleimide.

Useful polyols that may be used to form the epoxy-adduct include diols,trials, tetraols and higher functional polyols. The polyols can be basedon a polyether chain derived from ethylene glycol, propylene glycol,butylenes glycol, hexylene glycol and the like and mixtures thereof. Thepolyol can also be based on a polyester chain derived from ring openingpolymerization of caprolactone. Suitable polyols may also includepolyether polyol, polyurethane polyol, polyurea polyol, acrylic polyol,polyester polyol, polybutadiene polyol, hydrogenated polybutadienepolyol, polycarbonate polyols, polysiloxane polyol, and combinationsthereof. Polyamines corresponding to polyols can also be used, and inthis case, amides instead of carboxylic esters will be formed with acidsand anhydrides.

Suitable diols that may be utilized to form the epoxy-adduct are diolshaving a hydroxyl equivalent weight of between 30 and 1000. Exemplarydiols having a hydroxyl equivalent weight from 30 to 1000 include diolssold under the trade name Terathane®, including Terathane® 250,available from Invista. Other exemplary diols having a hydroxylequivalent weight from 30 to 1000 include ethylene glycol and itspolyether diols, propylene glycol and its polyether diols, butylenesglycol and its polyether diols, hexylene glycols and its polyetherdiols, polyester diols synthesized by ring opening polymerization ofcaprolactone, and urethane diols synthesized by reaction of cycliccarbonates with diamines. Combination of these diols and polyether diolsderived from combination various diols described above could also beused. Dimer diols may also be used including those sold under tradenames Pripol® and Solvermol™ available from Cognis Corporation.

Polytetrahydrofuran-based polyols sold under the trade name Terathane®,including Terathane® 650, available from Invista, may be used. Inaddition, polyols based on dimer diols sold under the trade namesPripol® and Empol®, available from Cognis Corporation, or bio-basedpolyols, such as the tetrafunctional polyol Agrol 4.0, available fromBioBased Technologies, may also be utilized.

Useful anhydride compounds to functionalize the polyol with acid groupsinclude hexahydrophthalic anhydride and its derivatives (e.g. methylhexahydrophthalic anhydride); phthalic anhydride and its derivatives(e.g. methyl phthalic anhydride); maleic anhydride; succinic anhydride;trimelletic anhydride; pyromelletic dianhydride (PMDA);3,3′,4,4′-oxydiphthalic dianhydride (ODPA); 3,3′,4,4′-benzopheronetetracarboxylic dianhydride (BTDA); and 4,4′-diphthalic(hexamfluoroisopropylidene) anhydride (6FDA). Useful diacid compounds tofunctionalize the polyol with acid groups include phthalic acid and itsderivates (e.g. methyl phthalic acid), hexahydrophthalic acid and itsderivatives (e.g. methyl hexahydrophthalic acid), maleic acid, succinicacid, adipic acid, etc. Any diacid and anhydride can be used; however,anhydrides are preferred.

In one embodiment, the polyol comprises a diol, the anhydride and/ordiacid comprises a monoanhydride or a diacid, and the first epoxycompound comprises a diepoxy compound, wherein the mole ratio of diol,monoanhydride (or a diacid), and diepoxy compounds in the epoxy-adductmay vary from 0.5:0.8:1.0 to 0.5:1.0:6.0.

In another embodiment, the polyol comprises a diol, the anhydride and/ordiacid comprises a monoanhydride or a diacid, and the first epoxycompound comprises a diepoxy compound, wherein the mole ratio of diol,monoanhydride (or a diacid), and diepoxy compounds in the epoxy-adductmay vary from 0.5:0.8:0.6 to 0.5:1.0:6.0.

In another embodiment, a second epoxy compound of the first component(a), wherein the first component (a) includes at least two epoxycompounds, is a diepoxide compound that has an epoxy equivalent weightof between about 150 and about 1000. Suitable diepoxides having an epoxyequivalent weight of between about 150 and about 1000 includepolyglycidyl ethers of Bisphenol A, such as Epon® 828 and 1001 epoxyresins, and Bisphenol F diepoxides, such as Epon® 862, which arecommercially available from Hexion Specialty Chemicals, Inc.

In another embodiment, the second epoxy compound of the first component(a) is a diepoxide compound or a higher functional epoxide(collectively, a “polyepoxide”), including polyglycidyl ethers ofpolyhydric alcohols, polyglycidyl esters of polycarboxylic acids,polyepoxides that are derived from the epoxidation of an olefinicallyunsaturated alicyclic compound, polyepoxides containing oxyalkylenegroups in the epoxy molecule, and epoxy novolac resins.

Still other non-limiting second epoxy compounds include epoxidizedBisphenol A novolacs, epoxidized phenolic novolacs, epoxidized cresylicnovolac, and triglycidyl p-aminophenol bismaleimide.

In another embodiment, the second epoxy compound of the first component(a) comprises an epoxy-dimer acid adduct. The epoxy-dimer acid adductmay be formed as the reaction product of reactants comprising adiepoxide compound (such as a Bisphenol A epoxy compound) and a dimeracid (such as a C36 dimer acid).

In another embodiment, the second epoxy compound of the first component(a) comprises a carboxyl-terminated butadiene-acrylonitrile copolymermodified epoxy compound.

Useful amine compounds that may be used include primary amines,secondary amines, tertiary amines, and combinations thereof. Usefulamine compounds that can be used include diamines, triamines,tetramines, and higher functional polyamines.

Suitable primary amines include alkyl diamines such as1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane,neopentyldiamine, 1,8-diaminooctane, 1,10-diaminodecane,1,-12-diaminododecane and the like; 1,5-diamino-3-oxapentane,diethylene-triamine, triethylenetetramine, tetraethylenepentamine andthe like; cycloaliphatic diamines such as1,2-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane,1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane and thelike; aromatic alkyl diamines such as 1,3-bis(aminomethyl)benzene(m-xylene diamine) and 1,4-bis(aminomethyl)benzene (p-xylenediamine) andtheir reaction products with epichlorohydrin such as Gaskamine 328 andthe like; amine-terminated polyethyleneglycol such as HuntsmanCorporation Jeffamine ED series and amine-terminated polypropyleneglycol such as Huntsman Corporation Jeffamine D series; andamine-terminated polytetrahydrofurane such as Huntsman Jeffamine EDRseries. Primary amines having functionality higher than 2 include, forexample, the Jeffamine T series, available from Huntsman Corporation,which are amine-terminated propoxylated trimethylolpropane or glyceroland aminated propoxylated pentaerythritols.

Still other amines that may be utilized include isophorone diamine,methenediamine, 4,8-diamino-tricyclio[5.2.1.0]decane andN-aminoethylpiperazine.

In certain embodiments, the amine compounds comprisetriethylenetetramine (TETA), isophorone diamine, 1,3bis(aminomethyl)cyclohexane, and polypropylene oxide-basedpolyetheramines.

In certain embodiments, the polypropylene oxide-based polyetheraminescomprise the Jeffamine series products available from Huntsman Chemicalof Houston, Tex. Jeffamine series products are polyetheraminescharacterized by repeating oxypropylene units in their respectivestructures.

In addition to the first component (a) and second component (b)described above, the 2K adhesive compositions of the present inventionalso comprise (c) graphenic carbon particles.

As used herein, the term “graphenic carbon particles” means carbonparticles having structures comprising one or more layers ofone-atom-thick planar sheets of sp2-bonded carbon atoms that are denselypacked in a honeycomb crystal lattice. The average number of stackedlayers may be less than 100, for example, less than 50. In certainembodiments, the average number of stacked layers is 30 or less, such as20 or less, 10 or less, or, in some cases, 5 or less. The grapheniccarbon particles may be substantially flat; however, at least a portionof the planar sheets may be substantially curved, curled, creased, orbuckled. The particles typically do not have a spheroidal or equiaxedmorphology.

In certain embodiments, the graphenic carbon particles present in thecompositions of the present invention have a thickness, measured in adirection perpendicular to the carbon atom layers, of no more than 10nanometers, no more than 5 nanometers, or, in certain embodiments, nomore than 4 or 3 or 2 or 1 nanometers, such as no more than 3.6nanometers. In certain embodiments, the graphenic carbon particles maybe from 1 atom layer up to 3, 6, 9, 12, 20 or 30 atom layers thick, ormore. In certain embodiments, the graphenic carbon particles present inthe compositions of the present invention have a width and length,measured in a direction parallel to the carbon atoms layers, of at least50 nanometers, such as more than 100 nanometers, in some cases such asmore than 100 nanometers up to 500 nanometers, or more than 100nanometers up to 200 nanometers. The graphenic carbon particles may beprovided in the form of ultrathin flakes, platelets or sheets havingrelatively high aspect ratios (aspect ratio being defined as the ratioof the longest dimension of a particle to the shortest dimension of theparticle) of greater than 3:1, such as greater than 10:1.

In certain embodiments, the graphenic carbon particles used in thecompositions of the present invention have relatively low oxygencontent. For example, the graphenic carbon particles used in certainembodiments of the compositions of the present invention may have anoxygen content of no more than 2 atomic weight percent, such as no morethan 1 atomic weight percent, or no more than 0.6 atomic weight, such asabout 0.5 atomic weight percent. The oxygen content of the grapheniccarbon particles can be determined using X-ray PhotoelectronSpectroscopy, such as is described in D. R. Dreyer et al., Chem. Soc.Rev. 39, 228-240 (2010).

In certain embodiments, the graphenic carbon particles used in thecompositions of the present invention have a relatively low bulkdensity. For example, the graphenic carbon particles used in certainembodiments of the present invention are characterized by having a bulkdensity (tap density) of less than 0.2 g/cm³, such as no more than 0.1g/cm³. For the purposes of the present invention, the bulk density ofthe graphenic carbon particles is determined by placing 0.4 grams of thegraphenic carbon particles in a glass measuring cylinder having areadable scale. The cylinder is raised approximately one-inch and tapped100 times, by striking the base of the cylinder onto a hard surface, toallow the graphenic carbon particles to settle within the cylinder. Thevolume of the particles is then measured, and the bulk density wascalculated by dividing 0.4 grams by the measured volume, wherein thebulk density is expressed in terms of g/cm³.

In certain embodiments, the graphenic carbon particles used in thecompositions of the present invention have a B.E.T. specific surfacearea of at least 50 square meters per gram, such as from 50 to 1000square meters per gram or from 50 to 600 square meters per gram, or, insome cases, 200 to 1000 square meters per grams or 200 to 400 squaremeters per gram. As used herein, the term “B.E.T. specific surface area”refers to a specific surface area determined by nitrogen adsorptionaccording to the ASTMD 3663-78 standard based on theBrunauer-Emmett-Teller method described in the periodical “The Journalof the American Chemical Society”, 60, 309 (1938).

In certain embodiments, the graphenic carbon particles used in thecompositions of the present invention have a Raman spectroscopy 2D/Gpeak ratio of at least 1.1. As used herein, the term “2D/G peak ratio”refers to the ratio of the intensity of the 2D peak at 2692 cm⁻¹ to theintensity of the G peak at 1,580 cm⁻¹.

In certain embodiments, the graphenic carbon particles used in thecompositions of the present invention have a compressed density and apercent densification that is less than the compressed density andpercent densification of graphite powder and certain types ofsubstantially flat graphenic carbon particles. Lower compressed densityand lower compression densification are each believed to contribute tobetter dispersion and rheological properties in adhesive compositionsthan correspondingly higher compressed density and higher compressiondensification. In certain of these embodiments, the compressed densityof the graphenic carbon particles of the present invention is 0.9 orless, such as less than about 0.8, such as less than about 0.7, such asfrom 0.6 to 0.7. In certain embodiments, the percent compressiondensification of the graphenic carbon particles of the present inventionis less than 40%, such as less than 30%, such as from 25 to 30%.

For purposes of the present invention, the compressed density ofgraphenic carbon particles is calculated from a measured thickness of agiven mass of the particles after compression. Specifically, forpurposes of the present invention, the measured thickness is determinedby subjecting 0.1 gram of the graphenic carbon particles to cold pressunder 15,000 pounds of force in a 1.3 centimeter die for 45 minutes(contact pressure=500 MPa [Mega-Pascal] pressure). The compresseddensity of the graphenic carbon particles is then calculated from thismeasured thickness according to the following formula:Compressed Density (g/cm³)=(0.1 grams graphenic carbonparticles)/(n*(1.3 cm/2)²*(measured thickness in cm)

The percent densification of the graphenic carbon particles isdetermined as the ratio of the determined or observed compressed densityof the graphenic carbon particles (as determined in the previousparagraph) to the density of graphite (graphite density=2.2).

In certain other embodiments, the graphenic carbon particles of thepresent invention has a measured bulk liquid conductivity of at least100 microSiemens, such as at least 120 microSiemens, such as at least140 microSiemens immediately after mixing and at later points in time,such as at 10 minutes, or 20 minutes, or 30 minutes, or 40 minutes. Forthe purposes of the present invention, the bulk liquid conductivity ofthe graphenic carbon particles is determined as follows. First, a 0.5%solution of graphenic carbon particles in butyl cellosolve (the sample)is sonicated for 30 minutes with a bath sonicator. Immediately followingsonication, the sample is placed in a standard calibrated electrolyticconductivity cell (K=1). A Fisher Scientific AB 30 conductivity meter isintroduced to the sample to measure the conductivity of the sample. Theconductivity is plotted over the course of about 40 minutes.

The graphenic carbon particles utilized in the compositions of thepresent invention can be made, for example, by thermal processes, suchas by using the apparatus and method described in U.S. patentapplication Ser. No. 13/249,315 at [0022] to [0048], the cited portionof which being incorporated herein by reference, in which (i) one ormore hydrocarbon precursor materials capable of forming a two-carbonspecies (such as n-propanol, ethane, ethylene, acetylene, vinylchloride, 1,2-dichloroethane, allyl alcohol, propionaldehyde, and/orvinyl bromide) is introduced into a thermal zone (such as a plasma); and(ii) the hydrocarbon is heated in the thermal zone to a temperature ofat least 1,000° C. to form the graphenic carbon particles. In addition,the graphenic carbon particles can be made by using the apparatus andmethod described in U.S. patent application Ser. No. 13/309,894 at[0015] to [0042], the cited portion of which being incorporated hereinby reference, in which (i) a methane precursor material (such as amaterial comprising at least 50 percent methane, or, in some cases,gaseous or liquid methane of at least 95 or 99 percent purity or higher)is introduced into a thermal zone (such as a plasma); and (ii) themethane precursor is heated in the thermal zone to form the grapheniccarbon particles. Such methods can produce graphenic carbon particleshaving at least some, in some cases all, of the characteristicsdescribed above.

Without being bound by any theory, it is currently believed that theforegoing methods of manufacturing graphenic carbon particles areparticularly suitable for producing graphenic carbon particles havingrelatively low thickness and relatively high aspect ratio in combinationwith relatively low oxygen content, as described above. Moreover, suchmethods are currently believed to produce a substantial amount ofgraphenic carbon particles having a substantially curved, curled orbuckled morphology (referred to herein as a “3D morphology” or as a“substantially 3D morphology), as opposed to producing predominantlyparticles having a substantially two-dimensional (or flat) morphology.This characteristic is believed to be reflected in the previouslydescribed compressed density characteristics and is believed to bebeneficial in the adhesive composition applications of the presentinvention because, it is currently believed, when a significant portionof the graphenic carbon particles have a substantially 3-dimensionalmorphology, “edge to edge and” edge to face contact between grapheniccarbon particles within the composition may be promoted. This is thoughtto be because particles having a substantially 3-dimensional morphologyare less likely to be aggregated in the adhesive composition (due tolower Van der Waals forces) than particles having a two-dimensionalmorphology. Moreover, it is currently believed that even in the case of“face to face contact between the particles having a 3D morphology,since the particles may have more than one facial plane, the entireparticle surface is not engaged in a single “face to face interactionwith another single particle, but instead can participate ininteractions with one or the other particles, including other “face toface interactions, in other planes. As a result, graphenic carbonparticles having a 3D morphology are currently thought to provide thebest conductive pathway in the present compositions and are currentlythought to be useful for obtaining electrical conductivitycharacteristics sought by the present invention, particularly when thegraphenic carbon particles are present in the composition in therelatively low amounts described below. Also, graphenic carbon particleshaving a 3 D morphology are currently thought to provide for increasedsurface area for the particles, and hence increased oil absorptioncharacteristics and dispersibility of the graphenic carbon particles ascompared with graphenic carbon particles having a substantially flatmorphology, and hence improved rheology characteristics through the useof the graphenic carbon particles having the substantially 3-dimensionalmorphology, sought by the adhesive compositions of present invention,particularly when these graphenic carbon particles are present in thecomposition in the relatively low amounts described below. Improvedtheological features of these adhesive compositions, as illustrated inthe Examples below, may be realized in terms of increased shear thinningratio (at 25° C. and/or at 45° C.), improved viscosity recovery, and/orimproved Thixotropic index (the methods for determining each of thesevalues is described in the Examples supplied herein) as compared withadhesive compositions including graphenic carbon particles having asubstantially flat morphology (even at lower loading levels), orgraphite particles, or in the absence of graphenic carbon particles.

In addition, it is believed that the introduction of graphenic carbonparticles (c) of the present invention into a 2K adhesive composition inan effective amount may also provide improved mechanical properties,such as increased tensile modulus, while maintaining a glass transitiontemperature as compared with 2K adhesive composition of the samecomposition not including graphenic carbon particles.

In certain embodiments, graphenic carbon particles (c) of the presentinvention are roll-milled in an epoxy carrier resin, such as Epon® 828,for introduction to the 2K adhesive composition. In one exemplaryembodiment, a master-batch of graphenic carbon particles/added epoxyresin is formed by milling the graphenic carbon particles of the presentinvention into the epoxy resin at 10 weight percent or higherconcentration. A dispersing method includes typical pigment grind millssuch as three-roll mill, Eiger mill, Netsch/Premier mill and the like.

In certain embodiments, the amount (i.e. the effective amount) ofgraphenic carbon particles (c) included in certain 2K adhesivecompositions of the present invention utilized to achieve such improvedtheological properties and mechanical properties (such as increasedtensile modulus) is from about 1 to 10 weight percent, such as from 3 to7 weight percent, based on the total weight of the 2K adhesivecomposition.

In still another embodiment, reinforcement fillers may be added to theadhesive composition as a part of the first component or as a part ofthe second component, or both.

Useful reinforcement fillers that may be introduced to the adhesivecomposition to provide improved mechanical properties include fibrousmaterials such as fiberglass, fibrous titanium dioxide, whisker typecalcium carbonate (aragonite), and carbon fiber (which includes graphiteand carbon nanotubes). In addition, fiber glass ground to 5 microns orwider and to 50 microns or longer may also provide additional tensilestrength. More preferably, fiber glass ground to 5 microns or wider andto 100-300 microns in length is utilized. Preferably, such reinforcementfillers, if utilized, comprise from 0.5 to 25 weight percent of theadhesive composition.

In still another embodiment, fillers, thixotropes, colorants, tints andother materials may be added to the first or second component of theadhesive composition.

Useful thixotropes that may be used include untreated fumed silica andtreated fumed silica, Castor wax, clay, and organoclay. In addition,fibers such as synthetic fibers like Aramid® fiber and Kevlar® fiber,acrylic fibers, and engineered cellulose fiber may also be utilized.

Useful colorants or tints may include red iron pigment, titaniumdioxide, calcium carbonate, and phthalocyanine blue.

Useful fillers that may be used in conjunction with thixotropes mayinclude inorganic fillers such as inorganic clay or silica.

In still another embodiment, if needed, a catalyst may be introduced tothe adhesive composition, preferably as a part of the second component,to promote the reaction of the epoxide groups of first component andamine groups of the second component.

Useful catalysts that may be introduced to the adhesive compositioninclude Ancamide® products available from Air Products and productsmarketed as “Accelerators” available from the Huntsman Corporation. Oneexemplary catalyst is piperazine-base Accelerator 399 (AHEW: 145)available from the Huntsman Corporation. When utilized, such catalystscomprise between 0 and about 10 percent by weight of the total adhesivecomposition.

In addition, a catalytic effect may be expected from the reactionproduct of epichlorohydrin from the first component and the aminecompound from the second component in an equivalent ratio of 1:1. Anexample of such a product is Tetrad® and Tetrad®C available fromMitsubishi Gas Chemical Corporation.

In certain embodiments, rubber particles having a core/shell structuremay be included in the 2K adhesive formulation.

Suitable core-shell rubber particles are comprised of butadiene rubber;however, other synthetic rubbers could be employed; such asstyrene-butadiene and acrylonitrile-butadiene and the like. The type ofsynthetic rubber and the rubber concentration should not be limited aslong as the particle size falls under the specified range as illustratedbelow.

In certain embodiments, the average particle size of the rubberparticles may be from about 0.02 to 500 microns (20 nm to 500,000 nm).

In certain embodiments, the core/shell rubber particles are included inan epoxy carrier resin for introduction to the 2K adhesive composition.Suitable finely dispersed core-shell rubber particles in an averageparticle size ranging from 50 nm to 250 nm are master-batched in epoxyresin such as aromatic epoxides, phenolic novolac epoxy resin, BisphenolA and Bisphenol F diepoxide and aliphatic epoxides, which includecyclo-aliphatic epoxides at concentration ranging from 20 to 40 weightpercent. Suitable epoxy resins may also include a mixture of epoxyresins.

Exemplary non-limiting commercial core/shell rubber particle productsusing poly(butadiene) rubber particles having an average particle sizeof 100 nm that may be utilized in the 2K adhesive composition includesKane Ace MX 136 (a core-shell poly(butadiene) rubber dispersion (25%) inBisphenol F), Kane Ace MX 153 (a core-shell poly(butadiene) rubberdispersion (33%) in Epon® 828), Kane Ace MX 257 (a core-shellpoly(butadiene) rubber dispersion (37%) in Bisphenol A), and Kane Ace MX267 (a core-shell poly(butadiene) rubber dispersion (37%) in BisphenolF), each available from Kaneka Texas Corporation.

Exemplary non-limiting commercial core/shell rubber particle productsusing styrene-butadiene rubber particles having an average particle sizeof 100 nm that may be utilized in the 2K adhesive composition includesKane Ace MX 113 (a core-shell styrene-butadiene rubber dispersion (33%)in low viscosity Bisphenol A), Kane Ace MX 125 (a core-shellstyrene-butadiene rubber dispersion (25%) in Bisphenol A), Kane Ace MX215 (a core-shell styrene-butadiene rubber dispersion (25%) in DEN-438phenolic novolac epoxy), and Kane Ace MX 416 (a core-shellstyrene-butadiene rubber dispersion (25%) in MY-721 multi-functionalepoxy), Kane Ace MX 451 (a core-shell styrene-butadiene rubberdispersion (25%) in MY-0510 multi-functional epoxy), Kane Ace MX 551 (acore-shell styrene-butadiene rubber dispersion (25%) in Synasia 21Cyclo-aliphatic Epoxy), Kane Ace MX 715 (a core-shell styrene-butadienerubber dispersion (25%) in polypropylene glycol (MW 400)), eachavailable from Kaneka Texas Corporation.

In certain embodiments, the amount of core/shell rubber particlesincluded in the 2K adhesive formulation is from 0.1 to 10 weightpercent, such as from 0.5 to 5 weight percent, based on the total weightof the 2K adhesive composition.

1K Adhesives

As noted above, the present invention is also directed at 1K adhesivecompositions. A 1K, or one-component, adhesive composition is anadhesive composition that requires activation from an external energysource in order to cure (i.e. crosslink). In the absence of activationfrom the external energy source, the composition will remain largelyunreacted for long periods of time. In certain embodiments, all of thecomponents of a 1K adhesive composition may be stored together in asingle storage container. External energy sources that may be used topromote the curing reaction include radiation (i.e. actinic radiationsuch as ultraviolet light), heat, and/or moisture.

In certain embodiments, the 1K adhesive compositions of presentinvention comprise (a) a first component; (b) a second component thatchemically reacts with the first component upon activation from anexternal energy source; and (c) graphenic carbon particles, wherein thegraphenic carbon particles are the same graphenic carbon particleshaving a substantially 3-dimensional morphology as described above withrespect to the 2K adhesive compositions. For thermally curing 1Kadhesive compositions, the second component (b) comprises (d) aheat-activated latent curing agent.

Similar to the 2K adhesives, in certain embodiments, the introduction ofan effective amount of (c) graphenic carbon particles having asubstantially 3-dimensional morphology into a 1K adhesive composition ofthe present invention may provide improved mechanical properties, suchas increased tensile modulus, while maintaining a glass transitiontemperature as compared with 1K adhesives of the same composition notincluding the graphenic carbon particles.

In addition, in certain embodiments, and as confirmed by the Examplessupplied herein, the inclusion of an effective amount of grapheniccarbon particles having a substantially 3-dimensional morphology intocertain 1K adhesive compositions of the present invention may provideimproved rheological features of the resultant 1K adhesive compositionsas compared with 1K adhesives of the same composition not including thegraphenic carbon particles and as compared with 1K adhesive compositionsutilizing graphenic carbon particles having a substantially flatmorphology. These improved rheological features may include one or moreof: higher shear thinning rates (at 25° C. and/or at 45° C.), higherviscosity recovery, and higher Thixotropic Index for the resultant 1Kadhesive compositions.

In certain embodiments, the amount (i.e. the effective amount) ofgraphenic carbon particles included in certain 1K adhesive compositionsof the present invention utilized to achieve such improved rheologicalproperties and mechanical properties (such as increased tensile modulus)is from about 1 to 10 weight percent, such as from 3 to 7 weightpercent, based on the total weight of the 1K adhesive composition.

In certain other embodiments, the external energy source is a thermalsource such as an oven that heats the composition to a temperature aboveambient or slightly thermal temperatures.

The first component (a), in certain embodiments, comprises one or moreepoxy compound and/or epoxy-adducts. Suitable epoxy compounds and/orepoxy adducts include those epoxy compounds and epoxy adducts describedabove with respect to 2K adhesive systems and not repeated herein.

In certain embodiments, the heat-activated latent curing agent (d) thatmay be used include guanidines, substituted guanidines, substitutedureas, melamine resins, guanamine derivatives, cyclic tertiary amines,aromatic amines and/or mixtures thereof. The hardeners may be involvedstoichiometrically in the hardening reaction; they may, however, also becatalytically active. Examples of substituted guanidines aremethylguanidine, dimethylguanidine, trimethylguanidine,tetra-methylguanidine, methylisobiguanidine, dimethylisobiguanidine,tetramethylisobiguanidine, hexamethylisobiguanidine,heptamethylisobiguanidine and, more especially, cyanoguanidine(dicyandiamide). Representatives of suitable guanamine derivatives whichmay be mentioned are alkylated benzoguanamine resins, benzoguanamineresins or methoxymethylethoxymethylbenzoguanamine. In addition,catalytically-active substituted ureas may also be used. Suitablecatalytically-active substituted ureas includep-chlorophenyl-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea (fenuron) or3,4-dichlorophenyl-N,N-dimethylurea.

In certain other embodiments, the heat-activated latent curing agentalso or alternatively comprises dicyandiamide and3,4-dichlorophenyl-N,N-dimethylurea (also known as Diuron).

In certain embodiments, the 1K adhesive may include from 3 to 25 weightpercent, such as from 5 to 10 weight percent, of (b) the heat-activatedlatent curing agent, based on the total weight of the 1K adhesivecomposition of the 1K adhesive composition including parts (a)-(f).

In certain embodiments, the 1K adhesives of the present inventioncomprise: (a) an epoxy-capped flexibilizer; and (b) a heat-activatedlatent curing agent. In certain other embodiments, the 1K adhesives mayfurther comprise one or more of the following components: (c) anepoxy/CTBN (carboxyl-terminated butadiene acrylonitrile polymer) adduct;(d) an epoxy/dimer acid adduct; (e) rubber particles having a core/shellstructure; and (f) graphenic carbon particles. The graphenic carbonparticles (f) are the same graphenic carbon particles having asubstantially 3-dimensional morphology that are described above withrespect to the 2K adhesive systems and the generic 1K adhesive systemsdescribed above, while the components (a)-(e) are described furtherbelow.

In certain embodiments, the (a) epoxy-capped flexibilizer is formed asthe reaction product of reactants comprising a first epoxy compound, apolyol, and an anhydride and/or a diacid (i.e. an anhydride, a diacid,or both an anhydride and a diacid may be part of the reaction product)

Useful epoxy compounds that can be used include polyepoxides. Suitablepolyepoxides include polyglycidyl ethers of Bisphenol A, such as Epon®828 and 1001 epoxy resins, and Bisphenol F diepoxides, such as Epon®862, which are commercially available from Hexion Specialty Chemicals,Inc. Other useful polyepoxides include polyglycidyl ethers of polyhydricalcohols, polyglycidyl esters of polycarboxylic acids, polyepoxides thatare derived from the epoxidation of an olefinically unsaturatedalicyclic compound, polyepoxides containing oxyalkylene groups in theepoxy molecule, and epoxy novolac resins. Still other non-limiting firstepoxy compounds include epoxidized Bisphenol A novolacs, epoxidizedphenolic novolacs, epoxidized cresylic novolac, and triglycidylp-aminophenol bismaleimide.

Useful polyols that may be used include diols, triols, tetraols andhigher functional polyols. The polyols can be based on a polyether chainderived from ethylene glycol, propylene glycol, butylenes glycol,hexylene glycol and the like and mixtures thereof. The polyol can alsobe based on a polyester chain derived from ring opening polymerizationof caprolactone. Suitable polyols may also include polyether polyol,polyurethane polyol, polyurea polyol, acrylic polyol, polyester polyol,polybutadiene polyol, hydrogenated polybutadiene polyol, polycarbonatepolyols, polysiloxane polyol, and combinations thereof. Polyaminescorresponding to polyols can also be used, and in this case, amidesinstead of carboxylic esters will be formed with acids and anhydrides.

Suitable diols that may be utilized are diols having a hydroxylequivalent weight of between 30 and 1000. Exemplary diols having ahydroxyl equivalent weight from 30 to 1000 include diols sold under thetrade name Terathane®, including Terathane® 250, available from Invista.Other exemplary diols having a hydroxyl equivalent weight from 30 to1000 include ethylene glycol and its polyether diols, propylene glycoland its polyether diols, butylenes glycol and its polyether diols,hexylene glycols and its polyether diols, polyester diols synthesized byring opening polymerization of caprolactone, and urethane diolssynthesized by reaction of cyclic carbonates with diamines. Combinationof these diols and polyether diols derived from combination variousdiols described above could also be used. Dimer diols may also be usedincluding those sold under trade names Pripol® and Solvermol™ availablefrom Cognis Corporation.

Polytetrahydrofuran-based polyols sold under the trade name Terathane®,including Terathane® 650, available from Invista, may be used. Inaddition, polyols based on dimer diols sold under the trade namesPripol® and Empol®, available from Cognis Corporation, or bio-basedpolyols, such as the tetrafunctional polyol Agrol 4.0, available fromBioBased Technologies, may also be utilized.

Useful anhydride compounds to functionalize the polyol with acid groupsinclude hexahydrophthalic anhydride and its derivatives (e.g. methylhexahydrophthalic anhydride); phthalic anhydride and its derivatives(e.g. methyl phthalic anhydride); maleic anhydride; succinic anhydride;trimellitic anhydride; pyromellitic dianhydride (PMDA);3,3′,4,4′-oxydiphthalic dianhydride (ODPA); 3,3′,4,4′-benzopheronetetracarboxylic dianhydride (BTDA); and 4,4′-diphthalic(hexamfluoroisopropylidene)anhydride (61′1)A). Useful diacid compoundsto functionalize the polyol with acid groups include phthalic acid andits derivatives (e.g. methyl phthalic acid), hexahydrophthalic acid andits derivatives (e.g. methyl hexahydrophthalic acid), maleic acid,succinic acid, adipic acid, etc. Any diacid and anhydride can be used;however, anhydrides are preferred.

In one embodiment, the polyol comprises a diol, the anhydride and/ordiacid comprises a monoanhydride or a diacid, and the first epoxycompound comprises a diepoxy compound, wherein the mole ratio of diol,monoanhydride (or diacid), and diepoxy compounds in the epoxy-cappedflexibilizer may vary from 0.5:0.8:1.0 to 0.5:1.0:6.0.

In another embodiment, the polyol comprises a diol, the anhydride and/ordiacid comprises a monoanhydride or a diacid, and the first epoxycompound comprises a diepoxy compound, wherein the mole ratio of diol,monoanhydride (or a diacid), and diepoxy compounds in the epoxy-cappedflexibilizer may vary from 0.5:0.8:0.6 to 0.5:1.0:6.0.

In certain embodiments, the (a) epoxy-capped flexibilizer comprises thereaction product of reactants comprising an epoxy compound, an anhydrideand/or a diacid, and a caprolactone. In certain other embodiments, adiamine and/or a higher functional amine may also be included in thereaction product in addition to the epoxy compound, caprolactone, andthe anhydride and/or a diacid.

Suitable epoxy compounds that may be used to form the epoxy-cappedflexibilizer include epoxy-functional polymers that can be saturated orunsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic orheterocyclic. The epoxy-functional polymers can have pendant or terminalhydroxyl groups, if desired. They can contain substituents such ashalogen, hydroxyl, and ether groups. A useful class of these materialsincludes polyepoxides comprising epoxy polyethers obtained by reactingan epihalohydrin (such as epichlorohydrin or epibromohydrin) with a di-or polyhydric alcohol in the presence of an alkali. Suitable polyhydricalcohols include polyphenols such as resorcinol; catechol; hydroquinone;bis(4-hydroxyphenyl)-2,2-propane, i.e., Bisphenol A;bis(4-hydroxyphenyl)-1,1-isobutane; 4,4-dihydroxybenzophenone;bis(4-hydroxyphenol)-1,1-ethane; bis(2-hydroxyphenyl)-methane and1,5-hydroxynaphthalene.

Frequently used polyepoxides include polyglycidyl ethers of Bisphenol A,such as Epon® 828 epoxy resin which is commercially available fromHexion Specialty Chemicals, Inc and having a number average molecularweight of about 400 and an epoxy equivalent weight of about 185-192.Other useful polyepoxides include polyglycidyl ethers of otherpolyhydric alcohols, polyglycidyl esters of polycarboxylic acids,polyepoxides that are derived from the epoxidation of an olefinicallyunsaturated alicyclic compound, polyepoxides containing oxyalkylenegroups in the epoxy molecule, epoxy novolac resins, and polyepoxidesthat are partially defunctionalized by carboxylic acids, alcohol, water,phenols, mercaptans or other active hydrogen-containing compounds togive hydroxyl-containing polymers.

Useful anhydride compounds that may be utilized includehexahydrophthalic anhydride and its derivatives (e.g. methylhexahydrophthalic anhydride); phthalic anhydride and its derivatives(e.g. methyl phthalic anhydride); maleic anhydride; succinic anhydride;trimellitic anhydride; pyromellitic dianhydride (PMDA);3,3′,4,4′-oxydiphthalic dianhydride (ODPA); 3,3′,4,4′-benzopheronetetracarboxylic dianhydride (BTDA); and 4,4′-diphthalic(hexamfluoroisopropylidene) anhydride (6FDA). Useful diacid compounds tofunctionalize the polyol with acid groups include phthalic acid and itsderivates (e.g. methyl phthalic acid), hexahydrophthalic acid and itsderivatives (e.g. methyl hexahydrophthalic acid), maleic acid, succinicacid, adipic acid, etc. Any diacid and anhydride can be used; however,anhydrides are preferred.

Useful caprolactones that can be used include caprolactone monomer,methyl, ethyl, and propyl substituted caprolactone monomer, andpolyester diols derived from caprolactone monomer. Exemplary polyesterdiols having a molecular weight from about 400 to 8000 include diolssold under the trade name CAPA®, including CAPA® 2085, available fromPerstorp.

In one embodiment, the caprolactone comprises a carprolactone monomer,the anhydride and/or diacid comprises a monoanhydride or a diacid, andthe first epoxy compound comprises a diepoxy compound, wherein the moleratio of caprolactone monomer, monoanhydride (or diacid), and diepoxycompounds in the epoxy-capped flexibilizer may vary Crum 0.5:0.8:1.0 to0.5:1.0:6.0.

In one embodiment, the caprolactone comprises a carprolactone monomer,the anhydride and/or diacid comprises a monoanhydride or a diacid, andthe first epoxy compound comprises a diepoxy compound, wherein the moleratio of caprolactone monomer, monoanhydride (or diacid), and diepoxycompounds in the epoxy-capped flexibilizer may vary from 0.5:0.8:0.6 to0.5:1.0:6.0.

In one embodiment, the caprolactone comprises a carprolactone monomer,the anhydride and/or diacid comprises a monoanhydride or a diacid, thediamine or higher functional amine comprises a diamine, and the firstepoxy compound comprises a diepoxy compound, wherein the mole ratio ofcaprolactone monomer, monoanhydride (or diacid), diamine and diepoxycompounds in the epoxy-capped flexibilizer may vary from 2:1:2:2 to3:1:3:3.

In certain embodiments, the (a) epoxy-capped flexibilizer comprises thereaction product of reactants comprising an epoxy compound and a primaryor secondary polyether amine.

Suitable epoxy compounds that may be used to form the epoxy-cappedflexibilizer include epoxy-functional polymers that can be saturated orunsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic orheterocyclic. The epoxy-functional polymers can have pendant or terminalhydroxyl groups, if desired. They can contain substituents such ashalogen, hydroxyl, and ether groups. A useful class of these materialsincludes polyepoxides comprising epoxy polyethers obtained by reactingan epihalohydrin (such as epichlorohydrin or epibromohydrin) with a di-or polyhydric alcohol in the presence of an alkali. Suitable polyhydricalcohols include polyphenols such as resorcinol; catechol; hydroquinone;bis(4-hydroxyphenyl)-2,2-propane, i.e., Bisphenol A;bis(4-hydroxyphenyl)-1,1-isobutane; 4,4-dihydroxybenzophenone;bis(4-hydroxyphenol)-1,1-ethane; bis(2-hydroxyphenyl)-methane and1,5-hydroxynaphthalene.

Frequently used polyepoxides include polyglycidyl ethers of Bisphenol A,such as Epon® 828 epoxy resin which is commercially available fromHexion Specialty Chemicals, Inc and having a number average molecularweight of about 400 and an epoxy equivalent weight of about 185-192.Other useful polyepoxides include polyglycidyl ethers of otherpolyhydric alcohols, polyglycidyl esters of polycarboxylic acids,polyepoxides that are derived from the epoxidation of an olefinicallyunsaturated alicyclic compound, polyepoxides containing oxyalkylenegroups in the epoxy molecule, epoxy novolac resins, and polyepoxidesthat are partially defunctionalized by carboxylic acids, alcohol, water,phenols, mercaptans or other active hydrogen-containing compounds togive hydroxyl-containing polymers.

Useful primary and secondary polyether amine compounds that can be usedto form the epoxy-capped flexibilizer include amine-terminatedpolyethyleneglycol such as Huntsman Corporation Jeffamine ED series andamine-terminated polypropylene glycol such as Huntsman CorporationJeffamine D series; and amine-terminated polytetrahydrofuran such asHuntsman Jeffamine EDR series. Primary amines having a functionalityhigher than 2 include, for example, the Jeffamine T series, availablefrom Huntsman Corporation, which are amine-terminated propoxylatedtrimethylolpropane or glycerol and aminated propoxylatedpentaerythritols.

In one embodiment, the epoxy compound comprises a diepoxide, and theprimary or secondary polyether amine comprises a difunctional amine,wherein the mole ratio of diepoxide to difunctional amine varies from2:0.2 to 2:1.

In certain embodiments, the 1K adhesive may include from 2 to 40 weightpercent, such as from 10 to 20 weight percent, of (a) the epoxy-cappedflexibilizer, based on the total weight of the 1K adhesive compositionof the 1K adhesive composition including parts (a)-(f), of any of theforms described above.

In still other related embodiments, the (a) the epoxy-cappedflexibilizer may comprise a mixture of any two or more of theepoxy-capped flexibilizers described above, wherein the total weightpercent of the mixture of the two or more of the epoxy-cappedflexibilizers comprises from 2 to 40 weight percent, such as from 10 to20 weight percent, based on the total weight of the 1K adhesivecomposition of the 1K adhesive composition including parts (a)-(f).

In certain embodiments, the heat-activated latent curing agent (b) thatmay be used include guanidines, substituted guanidines, substitutedureas, melamine resins, guanamine derivatives, cyclic tertiary amines,aromatic amines and/or mixtures thereof. The hardeners may be involvedstoichiometrically in the hardening reaction; they may, however, also becatalytically active. Examples of substituted guanidines aremethylguanidine, dimethylguanidine, trimethylguanidine,tetra-methylguanidine, methylisobiguanidine, dimethylisobiguanidine,tetramethylisobiguanidine, hexamethylisobiguanidine,heptamethylisobiguanidine and, more especially, cyanoguanidine(dicyandiamide). Representatives of suitable guanamine derivatives whichmay be mentioned are alkylated benzoguanamine resins, benzoguanamineresins or methoxymethylethoxymethylbenzoguanamine. In addition,catalytically-active substituted ureas may also be used. Suitablecatalytically-active substituted ureas includep-chlorophenyl-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea (fenuron) or3,4-dichlorophenyl-N,N-dimethylurea.

In certain other embodiments, the heat-activated latent curing agent (b)also or alternatively comprises dicyandiamide and3,4-dichlorophenyl-N,N-dimethylurea (also known as Diuron).

In certain embodiments, the 1K adhesive may include from 3 to 25 weightpercent, such as from 5 to 10 weight percent, of (b) the heat-activatedlatent curing agent, based on the total weight of the 1K adhesivecomposition of the 1K adhesive composition including parts (a)-(f).

As noted above, in certain embodiments, the 1K adhesive composition mayinclude (c) an epoxy/CTBN adduct. In certain embodiments, CTBN liquidpolymers undergo addition esterification reactions with epoxy resins,allowing them to serve as elastomeric modifiers to enhance impactstrength, peel strength, and crack resistance.

Suitable epoxy compounds that may be used to form the epoxy/CTBN adductinclude epoxy-functional polymers that can be saturated or unsaturated,cyclic or acyclic, aliphatic, alicyclic, aromatic or heterocyclic. Theepoxy-functional polymers can have pendant or terminal hydroxyl groups,if desired. They can contain substituents such as halogen, hydroxyl, andether groups. A useful class of these materials includes polyepoxidescomprising epoxy polyethers obtained by reacting an epihalohydrin (suchas epichlorohydrin or epibromohydrin) with a di- or polyhydric alcoholin the presence of an alkali. Suitable polyhydric alcohols includepolyphenols such as resorcinol; catechol; hydroquinone;bis(4-hydroxyphenyl)-2,2-propane, i.e., Bisphenol A;bis(4-hydroxyphenyl)-1,1-isobutane; 4,4-dihydroxybenzophenone;bis(4-hydroxyphenol)-1,1-ethane; bis(2-hydroxyphenyl)-methane and1,5-hydroxynaphthalene.

Frequently used polyepoxides include polyglycidyl ethers of Bisphenol A,such as Epon® 828 epoxy resin which is commercially available fromHexion Specialty Chemicals, Inc and having a number average molecularweight of about 400 and an epoxy equivalent weight of about 185-192.Other useful polyepoxides include polyglycidyl ethers of otherpolyhydric alcohols, polyglycidyl esters of polycarboxylic acids,polyepoxides that are derived from the epoxidation of an olefinicallyunsaturated alicyclic compound, polyepoxides containing oxyalkylenegroups in the epoxy molecule, epoxy novolac resins, and polyepoxidesthat are partially defunctionalized by carboxylic acids, alcohol, water,phenols, mercaptans or other active hydrogen-containing compounds togive hydroxyl-containing polymers.

In certain embodiments, at least a portion, often at least 5 percent byweight, of the polyepoxide has been reacted with a carboxyl-terminatedbutadiene acrylonitrile polymer. In certain of these embodiments, thecarboxyl-terminated butadiene acrylonitrile polymers have anacrylonitrile content of 10 to 26 percent by weight. Suitable CTBNcompounds having an acrylonitrile content of 10 to 26 percent by weightthat may be used include Hypro 1300X8, Hypro 1300X9, Hypro 1300X13,Hypro 1300X18, and Hypro 1300X31, each available from Emerald SpecialtyPolymers, LLC of Akron, Ohio.

In certain other embodiments, the polyepoxide may be reacted with amixture of different carboxy-terminated butadiene acrylonitrilepolymers.

In certain embodiments, the functionality of the CTBN utilized is from1.6 to 2.4, and the epoxy compound is reacted with the CTBN material ina stoichiometric amount to form the epoxy/CTBN adduct.

In certain embodiments, the epoxy/CTBN adduct comprises from about 1 to20 weight percent, such as from 5 to 10 weight percent, of the totalweight of the 1K adhesive composition of the 1K adhesive compositionincluding parts (a)-(f).

As noted above, in certain embodiments, the 1K adhesive composition mayinclude (d) an epoxy/dimer acid adduct. In certain embodiments, theepoxy/dimer acid adduct may be formed by reacting an epoxy compound witha dimer acid.

Suitable epoxy compounds that may be used to form the epoxy/dimer acidadduct include epoxy-functional polymers that can be saturated orunsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic orheterocyclic. The epoxy-functional polymers can have pendant or terminalhydroxyl groups, if desired. They can contain substituents such ashalogen, hydroxyl, and ether groups. A useful class of these materialsincludes polyepoxides comprising epoxy polyethers obtained by reactingan epihalohydrin (such as epichlorohydrin or epibromohydrin) with a di-or polyhydric alcohol in the presence of an alkali. Suitable polyhydricalcohols include polyphenols such as resorcinol; catechol; hydroquinone;bis(4-hydroxyphenyl)-2,2-propane, i.e., Bisphenol A;bis(4-hydroxyphenyl)-1,1-isobutane; 4,4-dihydroxybenzophenone;bis(4-hydroxyphenol)-1,1-ethane; bis(2-hydroxyphenyl)-methane and1,5-hydroxynaphthalene.

Frequently used polyepoxides include polyglycidyl ethers of Bisphenol A,such as Epon® 828 epoxy resin which is commercially available fromHexion Specialty Chemicals, Inc. and having a number average molecularweight of about 400 and an epoxy equivalent weight of about 185-192.Other useful polyepoxides include polyglycidyl ethers of otherpolyhydric alcohols, polyglycidyl esters of polycarboxylic acids,polyepoxides that are derived from the epoxidation of an olefinicallyunsaturated alicyclic compound, polyepoxides containing oxyalkylenegroups in the epoxy molecule, epoxy novolac resins, and polyepoxidesthat are partially defunctionalized by carboxylic acids, alcohol, water,phenols, mercaptans or other active hydrogen-containing compounds togive hydroxyl-containing polymers.

As defined herein, dimer acids, or dimerized fatty acids, aredicarboxylic acids prepared by dimerizing unsaturated fatty acidsobtained from tall oil, usually on clay catalysts. Dimer acids usuallypredominantly contain a dimer of stearic acid known as C36 dimer acid. Asuitable dimer acid for use in forming the epoxy/dimer acid adduct ofthe present invention may be obtained from Croda, Inc. or from Cognis.

In certain embodiments, the epoxy compounds and dimer acids are reactedin stoichiometric amounts to form the epoxy/dimer acid adduct.

In certain embodiments, the epoxy/dimer acid adduct comprises from about1 to 15 weight percent, such as from 2 to 7 weight percent, of the totalweight of the 1K adhesive composition of the 1K adhesive compositionincluding parts (a)-(f).

As noted above, in certain embodiments, the 1K adhesive composition mayalso include (e) rubber particles having a core/shell structure.Suitable core shell rubber particles for use in the 1K adhesives are thesame as those described above with respect to the 2K adhesiveformulations and therefore not repeated herein.

In certain embodiments, the 1K adhesive may include from 0 to 75 weightpercent, such as from 5 to 60 weight percent, of (e) the rubberparticles having a core/shell structure, based on the total weight ofthe 1K adhesive composition including parts (a)-(f).

As noted above, in certain embodiments, the 1K adhesive composition mayalso include (f) graphenic carbon particles. Suitable graphenic carbonparticles for use in the 1K adhesives compositions are graphenic carbonparticles having a substantially 3-dimensional morphology as describedabove therefore not repeated herein. In certain embodiments, the 1Kadhesive may include from 1 to 10 weight percent, such as from 3 to 7weight percent, of (f) the graphenic carbon particles, based on thetotal weight of the 1K adhesive composition including parts (a)-(f).

In still other embodiments, the 1K adhesive formulation may also includeepoxy compounds or resins that are not incorporated into or reacted as apart of any of the components (a)-(f) above, including epoxy-functionalpolymers that can be saturated or unsaturated, cyclic or acyclic,aliphatic, alicyclic, aromatic or heterocyclic. The epoxy-functionalpolymers can have pendant or terminal hydroxyl groups, if desired. Theycan contain substituents such as halogen, hydroxyl, and ether groups. Auseful class of these materials includes polyepoxides comprising epoxypolyethers obtained by reacting an epihalohydrin (such asepichlorohydrin or epibromohydrin) with a di- or polyhydric alcohol inthe presence of an alkali. Suitable polyhydric alcohols includepolyphenols such as resorcinol; catechol; hydroquinone;bis(4-hydroxyphenyl)-2,2-propane, i.e., Bisphenol A;bis(4-hydroxyphenyl)-1,1-isobutane; 4,4-dihydroxybenzophenone;bis(4-hydroxyphenol)-1,1-ethane; bis(2-hydroxyphenyl)-methane and1,5-hydroxynaphthalene.

Frequently used polyepoxides include polyglycidyl ethers of Bisphenol A,such as Epon® 828 epoxy resin which is commercially available fromHexion Specialty Chemicals, Inc. and having a number average molecularweight of about 400 and an epoxy equivalent weight of about 185-192.Other useful polyepoxides include polyglycidyl ethers of otherpolyhydric alcohols, polyglycidyl esters of polycarboxylic acids,polyepoxides that are derived from the epoxidation of an olefinicallyunsaturated alicyclic compound, polyepoxides containing oxyalkylenegroups in the epoxy molecule, epoxy novolac resins, and polyepoxidesthat are partially defunctionalized by carboxylic acids, alcohol, water,phenols, mercaptans or other active hydrogen-containing compounds togive hydroxyl-containing polymers.

In still another embodiment, reinforcement fillers may be added to theadhesive composition. Useful reinforcement fillers that may beintroduced to the adhesive composition to provide improved mechanicalproperties include fibrous materials such as fiberglass, fibroustitanium dioxide, whisker type calcium carbonate (aragonite), and carbonfiber (which includes graphite and carbon nanotubes). In addition, fiberglass ground to 5 microns or wider and to 50 microns or longer may alsoprovide additional tensile strength. More preferably, fiber glass groundto 5 microns or wider and to 100-300 microns in length is utilized.Preferably, such reinforcement fillers, if utilized, comprise from 0.5to 25 weight percent of the 1K adhesive composition.

In still another embodiment, fillers, thixotropes, colorants, tints andother materials may be added to the 1K adhesive composition.

Useful thixotropes that may be used include untreated fumed silica andtreated fumed silica, Castor wax, clay, and organoclay. In addition,fibers such as synthetic fibers like Aramid® fiber and Kevlar® fiber,acrylic fibers, and engineered cellulose fiber may also be utilized.

Useful colorants or tints may include red iron pigment, titaniumdioxide, calcium carbonate, and phthalocyanine blue.

Useful fillers that may be used in conjunction with thixotropes mayinclude inorganic fillers such as inorganic clay or silica.

Exemplary other materials that may be utilized include, for example,calcium oxide and carbon black.

While the use of graphenic carbon particles having a three-dimensionalmorphology in the present invention is directed towards adhesivecompositions, it is specifically contemplated that these grapheniccarbon particles may also be suitable for use in other coatingcompositions, including any other coating composition that utilizesgraphite particles to improve some rheological or mechanical feature ofthe coating. For example, graphenic carbon particles having athree-dimensional morphology may be added in an effective amount toother types of coating compositions to provide improved mechanicalproperties, such as increased tensile modulus, while maintaining a glasstransition temperature, or to improve certain rheological features asdescribed above. Exemplary coating compositions wherein it may thus beutilized include, but are not limited to, primer compositions(particularly primer compositions having anti-chip properties, includingwaterborne primers), basecoat compositions, sealants, or any coatingcomposition comprising a film forming polymer.

Illustrating the invention are the following examples that are not to beconsidered as limiting the invention to their details. All parts andpercentages in the examples, as well as throughout the specification,are by weight unless otherwise indicated.

EXAMPLES Example A Preparation of Graphenic Carbon Particles

Graphenic carbon particles were produced using a DC thermal plasmareactor system. The main reactor system included a DC plasma torch(Model SG-100 Plasma Spray Gun commercially available from PraxairTechnology, Inc., Danbury, Conn.) operated with 60 standard liters perminute of argon carrier gas and 26 kilowatts of power delivered to thetorch. Methane precursor gas, commercially available from Airgas GreatLakes, Independent, Ohio, was fed to the reactor at a rate of 5 standardliters per minute about 0.5 inch downstream of the plasma torch outlet.Following a 14 inch long reactor section, a plurality of quench streaminjection ports were provided that included 6⅛ inch diameter nozzleslocated 60° apart radially. Quench argon gas was injected through thequench stream injection ports at a rate of 185 standard liters perminute. The produced particles were collected in a bag filter. The totalsolid material collected was 75 weight percent of the feed material,corresponding to a 100 percent carbon conversion efficiency. Analysis ofparticle morphology using Raman analysis and high resolutiontransmission electron microscopy (TEM) indicates the formation of agraphenic layer structure with average thickness of less than 3.6 nm.The Raman plot shown in FIG. 1 demonstrates that graphenic carbonparticles were formed by virtue of the sharp and tall peak at 2692 onthe plot versus shorter peaks at 1.348 and 1580. The TEM image of FIG. 2shows the thin plate-like graphenic carbon particles. The measuredB.E.T. specific surface area of the produced material was 270 squaremeters per gram using a Gemini model 2360 analyzer available fromMicromeritics Instrument Corp., Norcross, Ga. Composition analysis ofthe produced material showed 99.5 atomic weight % carbon and 0.5 atomicweight % oxygen using X-ray Photoelectron Spectroscopy (XPS) availablefrom Thermo Electron Corporation. The collected particles had a bulkdensity of about 0.05 g/cm³, a compressed density of 0.638 g/cm³ and apercent densification of 29%. The measured bulk liquid conductivity from0-40 minutes of a 0.5% solution of the collected graphenic carbonparticles in butyl cellosolve varied from 143 to 147 microSiemens.

Example B Evaluation of 2K Adhesives

In Example B, graphenic carbon particles were evaluated for rheologicalperformance in the first component of a 2K adhesive (Example 2) versus a2K adhesive containing no graphenic carbon particles (Example 1),commercially available graphenic carbon particles (Example 3) orgraphite (Example 4). The formulas evaluated are shown in Table 1:

TABLE 1 Part A (epoxy) Ex. 1 Ex. 2 Ex. 3 Ex. 4 Epon 828¹ 41.05 41.0541.05 41.05 Graphenic Carbon Particles² 2.64 xGnP C750 Graphenic carbon4.56 black³ Graphite⁴ 5.7 Epon 828/Terathane 12.1 12.1 12.1 12.1650/HHPA⁶ Wacker HDK H17⁶ 1 1 1 1 % Graphenic Carbon Particles or 0.00%4.60% 7.80% 9.50% Graphite in total formula ¹Bisphenol A-Epichlorohydrinresin available from Huntsman Advance Materials. ²Graphenic carbonparticles produced in Example A above. ³Commercially available from XGScience, Inc. The product data information of the C750 graphenic carbonparticles discloses a typical particle thickness of 5-15 nanometers, asurface area of 750 square meters per gram, an oxygen content of lessthan 2 atomic weight percent, and a bulk density of 0.03-0.15 g/cm³. Themeasured bulk liquid conductivity from 0-40 minutes of a 0.5% solutionof C750 graphenic particles in butyl cellosolve varied between 0.50 and0.55 microSiemens. The measured compressed density and percentdensification of the C750 graphenic carbon particles was 0.94-1.08 g/cm³and 42-49%. respectively. ⁴Graphite available from Sigma-Aldrich, whichhad a compressed density of 1.57 and a percent densification of 71.4%.⁵Epon 828/Terathane 650/Hexahydrophthalic anhydride adduct; EEW 412⁶Hydrophobic Fumed Silica available from Wacker Chemie AG

In these examples, Epon 828 and the graphenic carbon particles or thexGnP C750 graphenic carbon black particles (where utilized) werepre-mixed and roll-milled three times. The remainder of the ingredients,except the fumed silica, were added to the mixture and mixed in theSpeedMix DAC 600 FVZ for 1 minute at 2350 RPM. The fumed silica was thenadded to the mixture and mixed again for 1 minute at 2350 RPM. Finally,the mixture was mixed using a low shear motor under vacuum.

Examples 1-4 were then evaluated for shear thinning ratio based on aflow curve and for viscosity recovery. From these tests, a ThixotropicIndex can be determined for the adhesive sample.

Shear thinning ratio is a measurement to determine the degree to whichan adhesive will shear thin. This test utilizes an Aton-Paar Physica MCR301 Rheometer with 25 mm plate and 0.7 mm gap for evaluating theadhesive. In this test, viscosity of the sample is measured as afunction of increasing shear rate (0.01 to 1000 s⁻¹) in rotation mode.The viscosity is measured at 25° C. and 45° C., respective. In thistest, the adhesive sample is pre-sheared at 10 revolutions per secondfor 10 seconds prior to beginning of the test. As one of ordinary skillrecognizes, a higher shear thinning ratio at 25° C. and 45° C. is betterfor sprayability of the adhesive to a substrate.

Viscosity recovery curve testing is utilized to determine how theviscosity of an adhesive sample recovers after high shear, and therebyassesses the thixotropic behavior of an adhesive sample. In this test,an Anton-Paar Physica MCR 301 Rheometer with 25 mm plate and 0.7 mm gapis utilized to measure the viscosity as a function of time with thefollowing shear conditions:

T1: oscillation at 1 Hz with 5% strain for 5 minutes (low shear region);

T2: rotation at 5000 s⁻¹ for 5 min (high shear region); Stop for 2seconds;

T3: oscillation at 1 Hz with 5% strain for 8 min (low shear region).

The rotational mode high shear region (T2) represents spraying action,following oscillation mode, while the low shear region (T3) representsthe viscosity of the sample after it is spray applied onto the substrate(immediately after application (10.2 minutes) and at 17 minutes). The T3value at 17 minutes (hereinafter referred to as “viscosity recovery”) isindicative of the sag resistance of the adhesive, and thus a higherviscosity recovery suggests an increased sag resistance for the adhesivesample over a lower viscosity recovery. An increased sag resistance forthe adhesive sample (i.e. a higher value for the viscosity recovery), asone of ordinary skill in the adhesive arts recognizes, is more desirablethan a lower value.

The Thixotropic Index is another method to measure the rheologicalproperties of an adhesive composition. The Thixotropic Indexlogarithmically compares the viscosity of the adhesive sample after 7minutes of recovery (i.e. at 17 minutes) versus the viscosity of thesample as it is being applied (i.e. immediately prior to recovery, or at10 minutes), or (Log 17 min/10 min). A higher calculated ThixotropicRatio is indicative of improved non-sagging performance of the adhesivecomposition after application to a substrate.

The results of the rheological testing of Examples 1-4 are summarized inTables 2 and 3 below and indicate that the adhesive sample includinggraphenic carbon particles (Example 2) exhibited a higher shear thinningratio at 45° C., a higher viscosity recovery ((T3) at 17 minutes), and ahigher calculated Thixotropic Index than the other representativesamples (Examples 1, 3 and 4). Example 2 also confirms that such resultswere achievable at lower loading of graphenic carbon particles than thecorresponding graphenic carbon particle loading (Example 3) or graphiteloading (Example 4) of the corresponding 2K adhesives.

TABLE 2 Shear Thinning Ratio at 25° C. and 45° C. Part A (epoxy) Ex. 1Ex. 2 Ex. 3 Ex. 4 Shear Thinning ratio @ 25° C. 1.53 1.31 1.51 1.71Shear Thinning ratio @ 45° C. 2.6 5.17 2.92 2.23

TABLE 3 Viscosity Recovery and Thixotropic Index Viscosity RecoveryViscosity, Pa · s 5 minutes @ low shear 61.9 89.4 113 80.8oscillation-T1 10 minutes @ high shear rotation- 1.73 2.63 2.2 2.48 T210.2 minutes @ low shear 7.91 62.3 17 13.6 oscillation-T3 17 minutes @low shear 40.4 167 96.8 58.3 oscillation-T3 Thixotropic Index (Log 1.371.8 1.64 1.37 17 min/10 min)As is apparent from the foregoing, certain 2K adhesive compositions ofthe present invention comprise a mixture comprising (a) a firstcomponent comprising, for example, one or more epoxy compounds and/orepoxy-adducts and (c) graphenic carbon particles, wherein that mixtureis stored separately from (b) a second component that chemically reactswith the first component. In certain of these compositions: (1) a shearthinning ratio at 45 degrees Celsius of the mixture comprising (a) and(c) is at least 20 percent greater than the shear thinning ratio at 45degrees Celsius of a comparative mixture comprising component (a) butnot including (c); (2) a viscosity recovery ((T3) at 17 minutes) of themixture comprising (a) and (c) is at least 3 times greater than theviscosity recovery ((T3) at 17 minutes) of a comparative mixturecomprising component (a) but not including (c); and/or (3) a ThixotropicIndex of the mixture comprising (a) and (c) is at least 25 percentgreater than the Thixotropic Index of a comparative mixture comprisingcomponent (a) but not including (c). As used in this context, the term“comparative mixture means a mixture that has the same ingredients inthe same amounts as another mixture to which it is being compared, withthe sole exception that, in the comparative mixture, (c) is not present.

Example C Evaluation of 1K Adhesives

In Example C, graphenic carbon particles of the present invention wereevaluated for rheological performance (Example 6) versus a 1K adhesivecontaining no graphenic carbon particles (Example 5) and versuscommercially available graphenic carbon particles (Example 7) at similarloading levels. The formulas evaluated are shown in Table 4.

TABLE 4 1K Structural adhesive Ex. 5 Ex. 6 Ex. 7 Epon 828¹ 51.7 51.729.7 Graphenic Carbon Particles² — 3.3 — xGnP C750 Graphenic 3.3 carbonblack³ Epon 828¹ 22 Epon 828/Terathane 10 10 10 650/ITHPA⁵Dicyandiamide⁷ 5.1 5.1 5.1 Diuron⁸ 0.35 0.35 0.35 Calcium Oxide⁹ 3.1 3.13.1 Wacker HDK H17⁶ 1 1 1 % Graphenic Carbon Particles 0.00% 4.43% 4.43%in total formula ⁷Commercially available from ALZ CHEM ⁸Commerciallyavailable from AT .7 CHEM ⁹Commercially available from MISSISSIPPI LIMECO

In these examples, Epon 828 and the graphenic carbon particles or thexGnP C750 graphenic carbon black particles (if included) were pre-mixedand roll-milled three times. The remainder of the ingredients, exceptthe fumed silica, were added to the mixture and mixed in the SpeedMixDAC 600 FVZ for 1 minute at 2350 RPM. The fumed silica was then added tothe mixture and mixed again for 1 minute at 2350 RPM. Finally, themixture was mixed for 5-8 minutes using a low shear motor under vacuum.

The results of the theological testing of Examples 5-7 are summarized inTable 5 below and indicate that the 1K adhesive samples includinggraphenic carbon particles (Examples 6 and 7) exhibited higher shearthinning ratios at 45° C., improved viscosity recovery ((T3) at 17minutes), and higher calculated Thixotropic Index than 1K adhesivesamples without graphenic carbon particles. In addition, the 1K adhesivesample having graphenic carbon particles (Example 6) in accordance withthe present invention exhibited similar shear thinning ratios at 25° C.and 45° C. and exhibited higher viscosity recovery ((T3) at 17 minutes)and a higher calculated Thixotropic Index than the correspondingrepresentative adhesive samples utilizing commercially availablegraphenic carbon particles (Example 7).

TABLE 5 Rheological Performance 1K Structural adhesive Ex. 5 Ex. 6 Ex. 7Shear Thinning ratio @ 25° C. 1.65 1.33 1.51 Shear Thinning ratio @ 45°C. 2.45 4.65 2.71 Viscosity Recovery Viscosity, Pa · s 5 min. @ lowshear oscillation-T1 69.2 102 97.8 10 min. @ high shear rotation-T2 1.82.45 2.28 10.2 min. @ low shear oscillation- 8.82 85.8 14.1 T3 17 min. @low shear oscillation-T3 38.7 186 65.4 Thixotropic Index 1.33 1.88 1.46As is apparent from the foregoing, certain 1K adhesive compositions ofthe present invention exhibit: (1) a shear thinning ratio at 45 degreesCelsius that is at least 20 percent greater than the shear thinningratio at 45 degrees Celsius of a comparative adhesive composition thatdoes not include the graphenic carbon particles; (2) a viscosityrecovery that is at least 2 times greater than the viscosity recovery ofa comparative adhesive composition that does not include the grapheniccarbon particles; and/or (3) a Thixotropic Index that is at least 20percent greater than the Thixotropic Index of a comparative adhesivecomposition that does not include the graphenic carbon particles. Asused in this context, the term “comparative adhesive composition” meansan adhesive composition that has the same ingredients in the sameamounts as another adhesive composition to which it is being compared,with the sole exception that, in the comparative adhesive composition,the graphenic carbon particles are not present.

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details of the presentinvention may be made without departing from the invention as defined inthe appended claims.

We claim:
 1. An adhesive composition comprising: (a) a first component;(b) a second component that chemically reacts with said first component;and (c) graphenic carbon particles comprising one or more stacked layersof one-atom-thick planar sheets of sp²-bonded carbon atoms that aredensely packed in a honeycomb crystal lattice having an oxygen contentof no more than 2 atomic weight percent, a substantially curved, curledor buckled morphology, and a Raman spectroscopy 2D/G peak ratio of atleast 1.1.
 2. The adhesive composition of claim 1, wherein saidgraphenic carbon particles are thermally produced.
 3. The adhesivecomposition of claim 1, wherein said graphenic carbon particles have athickness, measured in a direction perpendicular to at least one carbonatom layer, of no more than 10 nanometers.
 4. The adhesive compositionof claim 1, wherein said graphenic carbon particles have an aspect ratioof greater than 3:1.
 5. The adhesive composition of claim 1, whereinsaid graphenic carbon particles comprise from 1 to 10 weight percent ofthe total weight of the adhesive composition.
 6. The adhesivecomposition of claim 1, wherein said second component chemically reactswith said first component without the need for activation from anexternal energy source.
 7. The adhesive composition of claim 6, furthercomprising rubber particles having a core/shell structure.
 8. Theadhesive composition of claim 1, wherein a mixture comprising (a) and(c) is stored separately from (b), wherein a shear thinning ratio at 45degrees Celsius of the mixture is at least 20 percent greater than ashear thinning ratio at 45 degrees Celsius of a comparative mixturecomprising component (a) but not including (c) as measured by anAton-Paar Physica MCR 301 Rheometer with 25 mm plate and 0.7 mm gap. 9.The adhesive composition of claim 1, wherein a mixture comprising (a)and (c) is stored separately from (b), wherein a viscosity recovery((T3) at 17 minutes) of the mixture is at least 3 times greater than aviscosity recovery ((T3) at 17 minutes) of a comparative mixturecomprising component (a) but not including (c) as measured as a functionof time by an Aton-Paar Physica MCR 301 Rheometer with 25 mm plate and0.7 mm gap.
 10. The adhesive composition of claim 1, wherein a mixturecomprising (a) and (c) is stored separately from (b), wherein aThixotropic Index of the mixture is at least 25 percent greater than theThixotropic Index of a comparative mixture comprising component (a) butnot including (c) as determined by logarithmically comparing theviscosity of the adhesive sample after 7 minutes of recovery versus theviscosity of the sample as it is being applied.
 11. The adhesivecomposition of claim 1, wherein said second component chemically reactswith said first component after mixing and upon activation from anexternal energy source.
 12. The adhesive composition of claim 11,wherein said second component (b) comprises a heat activated latentcuring agent.
 13. The adhesive composition of claim 1, wherein a 0.5% byweight solution of said graphenic carbon particles in butyl cellosolvehas a bulk liquid conductivity of at least 100 microSiemens as measuredby a Fisher Scientific AB 30 conductivity meter.
 14. A method forforming a bonded substrate comprising: applying the adhesive compositionof claim 1 to a first substrate; contacting a second substrate to theadhesive composition such that the adhesive composition is locatedbetween said first substrate and said second substrate; and curing theadhesive composition.
 15. A coating composition comprising: a filmforming polymer; and graphenic carbon particles comprising one or morestacked layers of one-atom-thick planar sheets of sp²-bonded carbonatoms that are densely packed in a honeycomb crystal lattice having anoxygen content of no more than 2 atomic weight percent, a substantiallycurved, curled or buckled morphology, and a Raman spectroscopy 2D/G peakratio of at least 1.1.
 16. A coating comprising: the cured coatingcomposition of claim
 15. 17. An adhesive comprising: the cured adhesivecomposition of claim
 1. 18. A method of making a composition comprising:mixing thermally produced graphenic carbon particles and an adhesivecomponent comprising an epoxy, wherein the graphenic carbon particlescomprise one or more stacked layers of one-atom-thick planar sheets ofsp²-bonded carbon atoms that are densely packed in a honeycomb crystallattice having an oxygen content of no more than 2 atomic weightpercent, a substantially curved, curled or buckled morphology, and aRaman spectroscopy 2D/G peak ratio of at least 1.1.
 19. The method ofclaim 18, wherein the thermally produced graphenic carbon particles areproduced by heating at least one hydrocarbon precursor material capableof forming a two-carbon species in a thermal zone at a temperature of atleast 1000° C.
 20. The method of claim 18, wherein the thermallyproduced graphenic carbon particles are produced by heating a methaneprecursor material in a thermal zone at a temperature of at least 1000°C.
 21. The method of claim 19, wherein the thermal zone is at atemperature of from greater than 3,500° C. to 20,000° C.
 22. The methodof claim 20, wherein the thermal zone is at a temperature of fromgreater than 3,500° C. to 20,000° C.